Checking Tire Inflation Pressure

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When vehicle manufacturers select a tire size for a vehicle, they evaluate the vehicle's gross axle weights, the anticipated use of the tire, and the tire diameter and width. Adjustments to these factors give the manufacturer a way to improve handling and appearance. This is especially true for performance tire sizes. The size selected is rarely limited to only one capability (i.e. carrying the vehicle's weight).

The tire usually needs to have additional load capacity as well. This extra capacity is important because without it all of the tire's performance would be used up just carrying the weight of the vehicle and little would be left for durability at high speeds or responsive handling. For all vehicles produced since 1968, the original tires sizes and inflation pressures (including the spare) are listed on a vehicle placard. This placard can be located on:

Additionally, some manufacturers also list the original tire pressure in the vehicle's owner's manual. If a car's inflation pressure has varied from that which was recommended by the manufacturer, it's likely that the tire's wear and performance characteristics have also changed.

Under-inflation

If your vehicle's tires are under inflated by only 6 psi it could lead to tire failure. Additionally, the tire's tread life could be reduced by as much as 25%. Lower inflation pressure will allow the tire to deflect (bend) more as it rolls. This will build up internal heat, increase rolling resistance and cause a reduction in fuel economy of up to 5%. You would find a significant loss of steering precision and cornering stability. While 6 psi doesn't seem excessively low, remember, it usually represents about 20% of the tire's recommended pressure.

Over-inflation

If your tires are over inflated by 6 psi, they could be damaged more easily when running over pot holes or debris in the road. Higher inflated tires cannot isolate road irregularities well causing them to ride harsher. However, higher inflation pressures usually provide an improvement in steering response and cornering stability up to a point. This is why participants who use street tires in autocrosses, track events and road races, run higher than normal inflation pressures.

Tire Replacement

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While I was walking in a parking lot the other day I noticed this tire (when you own an auto repair shop you are CONSTANTLY looking for repairs that need to be done on ALL the cars you come in contact with).

This tire at first appears to be in good shape and have plenty of tread life left, but that is wear (hehe – wear – not where) you would be wrong.

When inspecting your tires for potential wear problems you should always look at the lowest part of the tread, that will be the area that will "show steel" first.

The steel is from the steel belts under the rubber that give the tire strength. When the rubber wears down the steel cord or “belts” will begin to show and then it is just a matter of time before the tire blows or goes flat do to the air loss.

In this particular case this tire is worn almost to the steel cord on the outside of the tire tread (wear – hahaha – I crack myself up – my finger is pointing) The rest of the tire tread looks really good, but unfortunately this car needs a new tire, and needs one now.

This tire will become dangerous very soon as the steel cord will begin to show. Do you see it, the worn out smooth edge that my finger is pointing to? That used to be tread, now it is worn off and is smooth...and just below that thin layer or rubber is the steel belts.

This tire probably got in this position due to a lack of front end alignments, something could be out of whack causing the tire to wear like this or it could be from taking corners too fast.

If you are tired of ordinary car rims it might be time for some custom wheels or a whole new wheel package for your vehicle. Not only do chrome wheels look good, they also improve your vehicles performance. Factory issued steel auto rims are heavy, while if you purchase chrome rims with an aluminum alloy base you improve the strength of your car rims and reduce wheel weight. When you decrease wheel weight you get overall improved cancelation and braking. Less weight means better performance.